With the establishment by CODEX of a 200 ng/g limit of inorganic arsenic (iAs) in polished rice grain, more analyses of iAs will be necessary to ensure compliance in regulatory and trade applications, to assess quality control in commercial rice production, and to conduct research involving iAs in rice crops. Although analytical methods using high-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) have been demonstrated for full speciation of As, this expensive and time-consuming approach is excessive when regulations are based only on iAs. We report a streamlined sample preparation and analysis of iAs in powdered rice based on heated extraction with 0.28 M HNO₃ followed by hydride generation (HG) under control of acidity and other simple conditions. Analysis of iAs is then conducted using flow-injection HG and inexpensive ICP-atomic emission spectroscopy (AES) or other detection means. A key innovation compared with previous methods was to increase the acidity of the reagent solution with 4 M HCl (prior to reduction of As⁵⁺ to As³⁺), which minimized interferences from dimethylarsinic acid. An inter-laboratory method validation was conducted among 12 laboratories worldwide in the analysis of six shared blind duplicates and a NIST Standard Reference Material involving different types of rice and iAs levels. Also, four laboratories used the standard HPLC-ICP-MS method to analyze the samples. The results between the methods were not significantly different, and the Horwitz ratio averaged 0.52 for the new method, which meets official method validation criteria. Thus, the simpler, more versatile, and less expensive method may be used by laboratories for several purposes to accurately determine iAs in rice grain.

中文翻译：

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实验室间验证一种廉价的简化方法来测量稻米中的无机砷

随着食典委对精制米粒中无机砷（iAs）的限量设定为200 ng / g，将需要对iAs进行更多分析，以确保法规和贸易应用的合规性，以评估商业稻米生产中的质量控制，并开展涉及iA的水稻作物研究。尽管已经证明了使用高效液相色谱-电感耦合等离子体质谱法（HPLC-ICP-MS）进行分析的方法可以实现As的完全形态分析，但是当法规仅基于iAs时，这种昂贵且耗时的方法是多余的。我们报告了基于0.28 M HNO ₃加热萃取的简化米饭中样品的制备和iAs的分析然后在酸度和其他简单条件下控制氢化物生成（HG）。然后使用流动注射HG和廉价的ICP原子发射光谱法（AES）或其他检测手段进行iAs分析。与以前的方法相比，一项关键的创新是用4 M HCl提高试剂溶液的酸度（在将As ⁵⁺还原为As ^3+之前），从而最大程度地减少了对二甲基亚砷酸的干扰。在全球12个实验室之间进行了实验室间方法验证，以分析6个共享盲目重复样品和涉及不同类型水稻和iAs水平的NIST标准参考物质。另外，四个实验室使用标准的HPLC-ICP-MS方法分析样品。方法之间的结果没有显着差异，新方法的Horwitz比率平均为0.52，符合官方方法验证标准。因此，实验室可以将更简单，更通用，更便宜的方法用于多种目的，以准确测定稻米中的iAs。